Patent GB-443016-A (GB)
Title: Improvements relating to start-stop selecting and translating mechanisms for printing telegraphs and other apparatus
IPC: H04L17/26
Filed: 1934-06-19
Abstract: 443,016. Type - printing telegraphy. GRIFFITH, R. G., Montclair, Crewes Avenue, Upper Warlingham, Surrey. June 19, 1934, No. 18093. [Classes 40 (iii) and 40 (v)] Errors due to interference or faulty operation are indicated in a system in which two or more versions of a signal are compared mechanically by a start-stop printer and an indication in the form of a perforation or a change in colour of the printing is produced if they fail to agree. In the arrangement shown, each signal combination is received by a magnet 1 and effects the setting of a typewheel 62. It is immediately repeated, and the repeated signal causes five abutments 65 to be positioned according to the second version of the signal. The setting of these abutments should be the counterpart of the setting of abutments 63 corresponding to the first version of the signal, and the printing of the letter is effected or not according as the abutments clear or interfere with one another when the lower abutments 65 are raised by the frames 77. Registration of first version of signal. The start signal moves the armature 2 to the left and trips the escapement 6, 7, so that shaft 8 performs a quarter-revolution during which the first version of the signal is received. Cam 12 acts through lever 21 to release the shaft 24 for half a revolution and cam 47 on this shaft acts through lever 48 to release a further shaft 45 for a quarter of a revolution. Cam 10 acts to disconnect the escapement control from armature 2, which then, according to the polarities of the five impulses of the received combination, permits or fails to permit the frame 26 to descend under control of the five-humped cam 31. Five cams 34, of which two are shown, permit five hooks 38 to come successively within reach of the frame 26, so that selected hooks are drawn down and act to release corresponding rockers 41. These rockers co-operate with cams 50 and arms 43, 44 to set five permutation bars 53, and these bars act through escapements 55, 56, and differential gearing 60 to position the typewheel 62. The rockers 41 are eventually restored by cams 51. Registration of second version of signal and comparison of versions. When the impulse-combination has been received, the shaft 24 performs a further half-revolution, either in response to a further start signal or, if this fails, under control of shaft 17 as described below. During this half-revolution the second version of the signal is set up on five additional permutation bars 54, and in this way the five abutments 65 are set so that, if the two versions of the signal agree, they lie clear of the five abutments 63, which are formed on the sectors 59 and so represent the first version of the signal. At the end of the double signal period a frame 77 is lifted by the action of a cam 75 on a shaft 69, which has been released by a cam 66 on the shaft 45. If the two versions of the signal agree, the frame 77 is able to rise and it moves the mask 81 so that the printing-hammer 73, controlled by cam 70, is able to press the tape 74 against the typewheel 62 through the mask. If, however, the two versions fail to agree, one or more pairs of abutments 63, 65 foul one another, the frame 77 is unable to rise, and the tape encounters a pin 82 which perforates a dot to indicate a fault. Modifications. (1) Instead of being repeated over the same channel, the two versions may be sent over two different channels and may be received by two different magnets 1, in which case independent cam shafts are provided for the two transmissions ; (2) Different code combinations may be employed in the two versions, and the cams 34, 35, controlling reception of the first and second versions respectively are then set in different angular relationships; (3) The signals may be repeated more than once, and in this case the abutments 63 are made wide enough to confront a corresponding number of abutments 64; (4) Instead of the mask 80 a device for enabling letters to be printed in red in case of a fault may be provided. Transmitter. At the transmitter one set of permutation bars may control two cam shafts, whereon the cams may be arranged in different angular settings so that different codes are used for the different versions of the signal; or both sets of cams may be on the same shaft. When the repetition system is to be disabled and the signals are to be sent in one version only, a keyboard-locking device may be provided to prevent the keys from being operated too fast. Electric synchronous movements. The start-stop shaft 8 is controlled by the received signals and in turn controls a second startstop shaft 24 which drives the selector mechanism. The phase relation between the starting times of the shafts 8 and 24 is regulated by manually adjusting the interponent 25, through which the cam 12 acts to trip the escapement 22, 23. If the start impulse for the second version of the signal fails, the shaft 24 is started nevertheless through the cam 12 acting through arm 13 on escapement 15, 16 to start the supplementary shaft 17, which in turn acts through cam 19 to trip the escapement 6, 7.